Wikipedia
Mohani ( Devanagari: मोहनि) is one of the most important festivals among the Newars which involves a packed itinerary of religious services, pilgrimages, family gatherings and outdoor celebrations lasting several days. Special dinners known as Nakhtya , to which all the relatives are invited, continue for weeks later. Mohani is the equivalent of Nepal's biggest festival Dasain, and there are similarities and differences between the two.
The festival has been variously described as a celebration of Hindu Goddess Durga slaying the demon Mahisasur, Goddess Chamunda destroying the demon Chunda and Indian emperor Ashoka renouncing arms in disgust after a particularly bloody battle and becoming a Buddhist. Mohani is celebrated according to the lunar calendar, so the dates are changeable. The main celebrations last for four days from the 8th to the 11th days of the bright half of Kaulā , the twelfth month in the lunar Nepal Era calendar.